diff --git a/m4/acinclude.m4 b/m4/acinclude.m4 --- a/m4/acinclude.m4 +++ b/m4/acinclude.m4 @@ -1903,15 +1903,13 @@ input:; %% EOF - $YACC conftest.yy > /dev/null 2>&1 + ## Older versions of bison only warn and exit with success. + octave_bison_output=`$YACC conftest.yy 2>&1 | grep api.prefix` ac_status=$? - if test $ac_status -eq 0; then + if test $ac_status -eq 0 && test -z "$octave_bison_output"; then octave_cv_bison_api_prefix_decl_style="$s" break fi - if test $ac_status -eq 0; then - break - fi done rm -f conftest.yy y.tab.h y.tab.c ])